1. Field of the Invention
The present invention relates to a module-type heat exchanger capable of coping with flexible manufacture and to a method of manufacturing the same.
2. Description of the Related Arts
A conventional mass production-type heat exchanger for cooling engine coolant has been constructed as seen in FIG. 10.
In this construction, both ends of flat tubes penetrate a pair of tube plates 18, with their penetrations being fixedly brazed to form a core, and members 12 are disposed on opposite end portions of the core. An open end of a tank body 19 is fitted to each tube plate 18, with the fitting portion being integrally brazed.
The tank body 19 has a port pipe 7, a filler neck 20 and a drain cock 16 mounted thereon.
Depending on various capacities and the conditions for sites to be mounted in automobiles, the heat exchangers for automobiles have had different widths and heights of the heat exchanger core and different positions and orientations of the port pipe and drain cock.
Separate molds were required for each different conditions to produce the heat exchangers corresponding to the design conditions. Such multiple molds resulted in higher production costs. In particular, among them, investments for molds of the tube plate 18 and the tank body 19 have caused a significant rise of the production costs. The design conditions for the heat exchangers have recently diversified more and more, which needs a flexible manufacture. Thus, the conventional method of manufacturing the heat exchanger has inevitably resulted in raised costs.
It is therefore the object of the present invention to provide a module-type heat exchanger capable of sharing as many components as possible so as not to incur a raised cost correspondingly to the flexible manufacture, and a method of manufacturing such a module-type heat exchanger.
In order to achieve the above object, according to a first aspect of the present invention, there is provided a module-type heat exchanger comprising a core, the core including a pair of header pipes each formed from a round pipe of a desired length and having engagement recesses previously formed in the inner surfaces at opposite open ends of the round pipe, the pair of header pipes each having a multiplicity of flat holes formed in parallel and at regular intervals in the peripheral surface, a multiplicity of flat tubes having opposite ends which are inserted into the flat holes, with their insertion portions being joined in a liquid tight manner, and a multiplicity of fins fixedly secured to the outer surface of each of the flat tubes; and end members such as end portions of a port pipe and an end cover which are fitted via O-rings for sealing to the openings of the header pipes in a liquid tight manner, wherein the end members at their fitting portions have outer peripheries which conform to the inner peripheries of the header pipes, the end members each including a claw formed protrusively on its outer periphery to be engaged with the engagement recess to provide a prevention of disengagement in the axial direction, and an annular recess formed in its outer periphery for receiving the O-ring.
In the module-type heat exchanger, the claw is preferably tapered in section to provide a disengagement prevention, with a space defined between the engagement recess and an opening edge of the header pipe being tapered toward the opening edge, and one or more claws and engagement recesses are preferably formed shorter than the perimeter in the circumferential direction so that they are prevented from rotating in the circumferential direction.
Preferably, a plurality of engagement recesses are arranged at regular intervals on the inner peripheral surface at the end portion of the header pipe, and the end member comprises at least a pair of port pipes, with the direction of extremity of the pipe being capable of selection in plural directions by the presence of the plurality of engagement recesses.
The header pipe may be produced by cutting an elongated round pipe, and the end member may be formed from a casting or an integral form of a synthetic resin.
In order to achieve the above object, according to a second aspect of the present invention there is provided a method of manufacturing the module-type heat exchanger, the method comprising the steps of severing an elongated round pipe having the same diameter to an appropriate length and cutting its inner surfaces at open ends and flat holes; making a core from the pair of header pipes of a desired length, flat tubes and fins; and preparing the end members such as the port pipes that conform to the inner surfaces at the open ends of the header pipe and fitting the end members to the opposite ends of the header pipe by way of O-rings for sealing in a liquid tight manner.